NATS 1740 Lecture Notes - Lecture 4: Ecliptic, Angular Diameter, Circumpolar Star

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Michael De Robertis, Alireza Rafiee

Document Summary

*understanding goals: - universe look like from earth. We can see 2,000 stars and the milky way (super dark + good vision or through telescope) Constellations: pattern of stars in the 3d sky => connects to astrology or mythological characters, cultures. + 3 dimensions: these stars are quite different distant from earth, a cross from most other vantage points. The celestial sphere (cs): all stars line on a sphere of immense size (earth is the centre), covered by the 88 constellations. The celestial equator: projection of earth"s equator on the cs. The celestial poles: projection of earth"s rotation axis on the cs (north & south celestial poles) Ecliptic: the sun moves along the sky, the sun"s path through the cs (earth"s orbital plane projected on the cs) + the c. e and ecliptic are tilted 23. 5 to one another. The milky way: we only know about this although there are other galaxies.